071cedc84e
Add a derive proc-macro for the `Zeroable` trait. The macro supports structs where every field implements the `Zeroable` trait. This way `unsafe` implementations can be avoided. The macro is split into two parts: - a proc-macro to parse generics into impl and ty generics, - a declarative macro that expands to the impl block. Suggested-by: Asahi Lina <lina@asahilina.net> Signed-off-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Link: https://lore.kernel.org/r/20230814084602.25699-4-benno.lossin@proton.me [ Added `ignore` to the `lib.rs` example and cleaned trivial nit. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
158 lines
5.8 KiB
Rust
158 lines
5.8 KiB
Rust
// SPDX-License-Identifier: Apache-2.0 OR MIT
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use proc_macro::{TokenStream, TokenTree};
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pub(crate) trait ToTokens {
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fn to_tokens(&self, tokens: &mut TokenStream);
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}
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impl<T: ToTokens> ToTokens for Option<T> {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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if let Some(v) = self {
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v.to_tokens(tokens);
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}
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}
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}
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impl ToTokens for proc_macro::Group {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend([TokenTree::from(self.clone())]);
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}
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}
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impl ToTokens for TokenTree {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend([self.clone()]);
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}
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}
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impl ToTokens for TokenStream {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend(self.clone());
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}
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}
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/// Converts tokens into [`proc_macro::TokenStream`] and performs variable interpolations with
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/// the given span.
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///
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/// This is a similar to the
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/// [`quote_spanned!`](https://docs.rs/quote/latest/quote/macro.quote_spanned.html) macro from the
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/// `quote` crate but provides only just enough functionality needed by the current `macros` crate.
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macro_rules! quote_spanned {
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($span:expr => $($tt:tt)*) => {{
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let mut tokens;
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#[allow(clippy::vec_init_then_push)]
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{
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tokens = ::std::vec::Vec::new();
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let span = $span;
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quote_spanned!(@proc tokens span $($tt)*);
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}
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::proc_macro::TokenStream::from_iter(tokens)
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}};
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(@proc $v:ident $span:ident) => {};
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(@proc $v:ident $span:ident #$id:ident $($tt:tt)*) => {
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let mut ts = ::proc_macro::TokenStream::new();
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$crate::quote::ToTokens::to_tokens(&$id, &mut ts);
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$v.extend(ts);
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident #(#$id:ident)* $($tt:tt)*) => {
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for token in $id {
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let mut ts = ::proc_macro::TokenStream::new();
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$crate::quote::ToTokens::to_tokens(&token, &mut ts);
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$v.extend(ts);
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}
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident ( $($inner:tt)* ) $($tt:tt)*) => {
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let mut tokens = ::std::vec::Vec::new();
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quote_spanned!(@proc tokens $span $($inner)*);
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$v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new(
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::proc_macro::Delimiter::Parenthesis,
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::proc_macro::TokenStream::from_iter(tokens)
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)));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident [ $($inner:tt)* ] $($tt:tt)*) => {
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let mut tokens = ::std::vec::Vec::new();
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quote_spanned!(@proc tokens $span $($inner)*);
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$v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new(
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::proc_macro::Delimiter::Bracket,
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::proc_macro::TokenStream::from_iter(tokens)
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)));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident { $($inner:tt)* } $($tt:tt)*) => {
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let mut tokens = ::std::vec::Vec::new();
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quote_spanned!(@proc tokens $span $($inner)*);
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$v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new(
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::proc_macro::Delimiter::Brace,
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::proc_macro::TokenStream::from_iter(tokens)
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)));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident :: $($tt:tt)*) => {
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$v.push(::proc_macro::TokenTree::Punct(
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::proc_macro::Punct::new(':', ::proc_macro::Spacing::Joint)
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));
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$v.push(::proc_macro::TokenTree::Punct(
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::proc_macro::Punct::new(':', ::proc_macro::Spacing::Alone)
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));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident : $($tt:tt)*) => {
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$v.push(::proc_macro::TokenTree::Punct(
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::proc_macro::Punct::new(':', ::proc_macro::Spacing::Alone)
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));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident , $($tt:tt)*) => {
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$v.push(::proc_macro::TokenTree::Punct(
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::proc_macro::Punct::new(',', ::proc_macro::Spacing::Alone)
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));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident @ $($tt:tt)*) => {
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$v.push(::proc_macro::TokenTree::Punct(
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::proc_macro::Punct::new('@', ::proc_macro::Spacing::Alone)
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));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident ! $($tt:tt)*) => {
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$v.push(::proc_macro::TokenTree::Punct(
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::proc_macro::Punct::new('!', ::proc_macro::Spacing::Alone)
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));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident ; $($tt:tt)*) => {
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$v.push(::proc_macro::TokenTree::Punct(
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::proc_macro::Punct::new(';', ::proc_macro::Spacing::Alone)
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));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident + $($tt:tt)*) => {
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$v.push(::proc_macro::TokenTree::Punct(
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::proc_macro::Punct::new('+', ::proc_macro::Spacing::Alone)
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));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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(@proc $v:ident $span:ident $id:ident $($tt:tt)*) => {
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$v.push(::proc_macro::TokenTree::Ident(::proc_macro::Ident::new(stringify!($id), $span)));
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quote_spanned!(@proc $v $span $($tt)*);
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};
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}
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/// Converts tokens into [`proc_macro::TokenStream`] and performs variable interpolations with
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/// mixed site span ([`Span::mixed_site()`]).
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///
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/// This is a similar to the [`quote!`](https://docs.rs/quote/latest/quote/macro.quote.html) macro
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/// from the `quote` crate but provides only just enough functionality needed by the current
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/// `macros` crate.
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///
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/// [`Span::mixed_site()`]: https://doc.rust-lang.org/proc_macro/struct.Span.html#method.mixed_site
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macro_rules! quote {
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($($tt:tt)*) => {
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quote_spanned!(::proc_macro::Span::mixed_site() => $($tt)*)
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}
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}
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